Drive systems incorporating clutches and brakes are known well in the art and have been used successfully for many years. The prior art designs of drives experienced problems with the braking and clutching systems as well as problems with the overall lubrication of the components of the drive. These prior art designs of drives utilize a plurality of dry friction plates to hold and/or release the various members of the drive system. Due to the wear between these friction plates, the drives require constant adjustment and replacement of the clutch and brake assemblies. Also, during the operation of these dry clutch and brake assemblies, a significant amount of heat is generated. This generation of heat combined with the excessive wear of the friction plates causes fading of the prior art brake and/or clutch assemblies. In addition to the problems of excessive heat generation and excessive wear of the prior art clutch and brake assemblies is the problem associated with supplying an adequate amount of lubrication to the various components of the drive system.
Oil shear brakes and clutches have been developed to overcome the problems associated with the earlier designs of drives incorporating dry friction plate brakes and clutches. In an oil shear clutch or brake system, over 90% of the start/stop inertia is absorbed by a thin, but positive oil film between the friction plates. This thin oil film thus results in little or no wear between the plates and also little or no fading of the clutch and/or brake assemblies. The thin oil film between the friction plates also operates to remove the heat generated during the stop/start cycles of the press. With the removal or elimination of the generated heat from the friction plates, there is no longer a practical limit on the drive trip rate or speed. The oil shear brake and clutch assemblies also eliminates the problems associated with lubrication of the various components of the drive as the drive housing is now filled with lubricating oil for the oil shear brake and clutch assemblies.
Drive systems incorporating oil shear brake and clutch assemblies have enjoyed wide acceptance in the drive system market. The continued development of these drive assemblies is directed towards providing a more compact and lower cost drive without sacrificing the performance characteristics of the drive system.